More than ordinary rinsing using pure water, cathode water obtained by electrolysis of dilute potassium carbonate aqueous solution (alkaline electrolyzed water: AEW) exhibits a stronger rinse effect for elimination of remaining sulfate ions when rinsing nickel-plated surfaces. This rinse effect was recognized even for AEW that was used 24 h after it was produced, but not 1 week after. Behaviors of hydrogen nanobubbles observed by dynamic light scattering revealed nanobubbles of about 128-nm diameter even 24 h after generation. The Ostwald ripening phenomenon was observed. Hydrogen nanobubbles in an open system changed: some shrank because of ripening, later dissolving in the aqueous solution and disappearing; others showed swelling and expansion. One week later, few nanobubbles smaller than 300 nm were observed. Rinse effects by AEW, which are attributable to the actions of hydrogen nanobubbles generated in AEW, occur because sulfate ions are cleaned and removed from the nickelplated surface.
The improvement in the surface cleanliness of electroplated nickel by rinsing in alkaline electrolyzed water (AEW) was determined. When the nickel plated sample was rinsed with the AEW, it was found that the amount of residual sulfate ion on the surface of a sample decreased approximately by half compared to one rinsed only with de-ionized pure water. Because nanosize hydrogen bubbles are present in the AEW, and the zeta-potential has a negative value, we then surmised that the mechanism of rinsing was as follows: The sulfate ions are selectively absorbed on the nanosize colloidal hydrogen bubbles, or substituted for anions absorbed on the hydrogen bubbles. The sulfate ions absorbed on the nickel surface then become detached. The detached sulfate ions are absorbed on the surface of the hydrogen bubbles, and negatively charge the hydrogen bubbles. It can be considered that any detached sulfate ions do not re-adhere due to the electrical repulsion force of the negatively charged nickel surface. Thus the sample is efficiently rinsed.
Summar yAn aerial application of neonicotinoid insecticide, thiacloprid, by a manned helicopter for controlling insect (Monochamus altermatus Hope) damage was carried out on pinewoods of Chikuma-city in Nagano Prefecture in June 2013. An investigation on thiacloprid drifts was conducted because many people reside near the applied area. Drifts in the air and in fallouts were collected at 4 locations near the applied area for three days after aerial spraying; and thiacloprid was quantified by liquid chromatography/tandem mass spectrometry. The result is that thiacloprid in the air was found from 4 locations at the maximum concentration of 1.9 ng/m 3 per day. Thiacloprid in fallouts was quantitatively detected from 3 locations at the maximum amount of 7900 ng/m 2 over three days. The maximum drift ratio was calculated to be 0.066 %. The results confirmed that a low-level drift occurred after the aerial application by a manned helicopter. The results suggest that the combination of air concentration measurements and fallout monitoring improved the evaluation of residential exposure to neonicotinoid insecticide.
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